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Solar Energy Generating Systems

Solar Energy Generating Systems

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Solar Energy Generating Systems (SEGS) is the largest solar energy generating facility in the world. It consists of nine solar power plants in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

's Mojave Desert
Mojave Desert
The Mojave Desert occupies a significant portion of southeastern California and smaller parts of central California, southern Nevada, southwestern Utah and northwestern Arizona, in the United States...

, where insolation
Insolation
Insolation is a measure of solar radiation energy received on a given surface area in a given time. It is commonly expressed as average irradiance in watts per square meter or kilowatt-hours per square meter per day...

 is among the best available in the United States. SEGS I–II (44 MW) are located at Daggett
Daggett, California
Daggett is an unincorporated town located in San Bernardino County, California in the United States. The town is located on Interstate 40 ten miles East of Barstow. The town has a population of about 200. The ZIP code is 92327 and the community is inside area code 760.-History:The town was...

, SEGS III–VII (150 MW) are installed at Kramer Junction
Kramer Junction, California
Kramer Junction is a small community in the Mojave Desert at the intersection of U.S. Route 395 and State Route 58.Solar Energy Generating Systems sites SEGS III-VII are located less than a mile to the northwest....

, and SEGS VIII–IX (160 MW) are placed at Harper Lake
Harper Lake
Harper Lake is a dry lake located in the Mojave Desert near the small community of Lockhart in northwestern San Bernardino County of Southern California...

. NextEra Energy Resources
NextEra Energy Resources
NextEra Energy Resources is an wholesale electricity supplier based in Juno Beach, Florida. It is a subsidiary of NextEra Energy, Inc. , a Fortune 200 company. Prior to 2009, NextEra Energy Resources was known as FPL Energy....

 operates and partially owns the plants located at Kramer Junction and Harper Lake.

Plants' scale and operations


The plants have a 354 MW installed capacity, making it the largest installation of solar plants of any kind in the world. The average gross solar output for all nine plants at SEGS is around 75 MWe
MWE
MWE may refer to:*Manufacturer's Weight Empty*McDermott Will & Emery*Midwest Express, an airline*Merowe Airport - IATA code*Multiword expressionMWe may refer to:*Megawatt electrical...

 — a capacity factor
Capacity factor
The net capacity factor or load factor of a power plant is the ratio of the actual output of a power plant over a period of time and its potential output if it had operated at full nameplate capacity the entire time...

 of 21%. In addition, the turbines can be utilized at night by burning natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

.

NextEra claims that the solar plants power 232,500 homes and displace 3,800 tons of pollution per year that would have been produced if the electricity had been provided by fossil fuels, such as oil.

The facilities have a total of 936,384 mirrors and cover more than 1600 acres (6.5 km²). Lined up, the parabolic mirrors would extend over 229 miles (368.5 km).

As an example of cost, in 2002, one of the 30 MW Kramer Junction sites required $90 million to construct, and its operation and maintenance cost is about $3 million per year (4.6 cents per kilowatt hour).

Principle of operation



The installation uses parabolic trough
Parabolic trough
A parabolic trough is a type of solar thermal energy collector. It is constructed as a long parabolic mirror with a Dewar tube running its length at the focal point. Sunlight is reflected by the mirror and concentrated on the Dewar tube...

 solar thermal technology along with natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

 to generate electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

. 90% of the electricity is produced by the sunlight
Sunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...

. Natural gas is only used when the solar power is insufficient to meet the demand from Southern California Edison, the distributor of power in southern California.

Mirrors


The parabolic mirrors are shaped like a half-pipe. The sun shines onto the panels made of glass, which are 94% reflective, unlike a typical mirror, which is only 70% reflective. The mirrors automatically track the sun throughout the day. The greatest source of mirror breakage is wind, with 3000 typically replaced each year. Operators can turn the mirrors to protect them during intense wind storms. An automated washing mechanism is used to periodically clean the parabolic reflective panels.

Heat transfer


The sunlight bounces off the mirrors and is directed to a central tube filled with synthetic oil
Synthetic oil
Synthetic oil is a lubricant consisting of chemical compounds that are artificially made . Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be synthesized from other raw materials...

, which heats to over 400 °C (752 °F). The reflected light focused at the central tube is 71 to 80 times more intense than the ordinary sunlight. The synthetic oil transfers its heat to water, which boils and drives the Rankine cycle
Rankine cycle
The Rankine cycle is a cycle that converts heat into work. The heat is supplied externally to a closed loop, which usually uses water. This cycle generates about 90% of all electric power used throughout the world, including virtually all solar thermal, biomass, coal and nuclear power plants. It is...

 steam turbine, thereby generating electricity. Synthetic oil is used to carry the heat (instead of water) to keep the pressure within manageable parameters.

Individual locations


The SEGS power plants were built by Luz Industries
BrightSource Energy
BrightSource Energy is an Oakland, California, corporation that designs, builds, finances and operates utility-scale solar power plants that deliver clean, low-cost solar energy to utility and industrial customers worldwide at prices that compete with fossil fuels.Greentech Media ranked...

, and commissioned between 1984 and 1991. After Luz Industries bankruptcy
Bankruptcy
Bankruptcy is a legal status of an insolvent person or an organisation, that is, one that cannot repay the debts owed to creditors. In most jurisdictions bankruptcy is imposed by a court order, often initiated by the debtor....

 in 1991 plants were sold to various investor groups as individual projects and expansion including three more plants was halted.

Kramer Junction employs about 95 people and 45 people work at Harper Lake.
SEGS plant history and operational data
Plant Year
built
Location Net turbine
capacity
Field
area
Oil
temperature
Gross solar production
of electricity (MWh)
(MW) (m²) (°C) 1996 average 1998–2002
SEGS I 1984 Daggett 14 82,960 307 19,900 16,500
SEGS II 1985 Daggett 30 165,376 316 36,000 32,500
SEGS III 1986 Kramer Jct. 30 230,300 349 64,170 68,555
SEGS IV 1986 Kramer Jct. 30 230,300 349 61,970 68,278
SEGS V 1987 Kramer Jct. 30 250,500 349 71,439 72,879
SEGS VI 1988 Kramer Jct. 30 188,000 391 71,409 67,758
SEGS VII 1988 Kramer Jct. 30 194,280 391 70,138 65,048
SEGS VIII 1989 Harper Lake 80 464,340 391 139,174 137,990
SEGS IX 1990 Harper Lake 80 483,960 141,916 125,036
Sources: Solargenix Energy, KJC Operating Company, IEEE, NREL

Harper Lake


SEGS VIII and SEGS IX, located at 35.0316°N 117.348 °W, are the largest solar power plants individually and collectively in the world. They were the last, the largest, and the most advanced of the nine plants at SEGS, designed to take advantage of the economies of scale. Construction of tenth plant is same locality was halted because of bankruptcy of Luz Industries, construction of approved eleventh and twelfth plants never started. Each of all three planned plants had 80 MW of installed capacity.

Kramer Junction


This location (35.0142°N 117.559 °W) receives an average of 340 days of sunshine per year, which makes it an ideal place for solar power generation. The average direct normal radiation
Direct insolation
Direct insolation is the solar irradiance measured at a given location on Earth with a surface element perpendicular to the Sun's rays, excluding diffuse insolation . Direct insolation is equal to the solar constant minus the atmospheric losses due to absorption and scattering...

 (DNR) is 7.44 kWh/m²/day (310 W/m²), one of the best in the nation.

Daggett


SEGS I and II are located at 34.8631°N 116.827 °W.

Accidents and incidents


In February 1999, a 900000 gallons (3,406.9 m³) therminol storage tank exploded at the SEGS II (Daggett) solar power plant, sending flames and smoke into the sky. Authorities were trying to keep flames away from two adjacent containers that held sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 and sodium hydroxide. The immediate area of 0.5 square miles (1.3 km²) was evacuated.

See also



  • List of concentrating solar thermal power companies
  • List of photovoltaic power stations
  • List of solar thermal power stations
  • Parabolic trough
    Parabolic trough
    A parabolic trough is a type of solar thermal energy collector. It is constructed as a long parabolic mirror with a Dewar tube running its length at the focal point. Sunlight is reflected by the mirror and concentrated on the Dewar tube...

  • Renewable energy in the United States
    Renewable energy in the United States
    Renewable energy accounted for 14.3 percent of the domestically produced electricity in the United States in the first six months of 2011. Hydroelectricity is the largest producer of renewable power in the United States. In 2009, the U.S...

  • Renewable portfolio standard
    Renewable Portfolio Standard
    A Renewable Portfolio Standard is a regulation that requires the increased production of energy from renewable energy sources, such as wind, solar, biomass, and geothermal...

  • Solar power
    Solar power
    Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available...

  • Solar power in the United States
    Solar power in the United States
    Solar power in the United States is an area of considerable activity and there are many utility-scale solar power plants. The largest solar power installation in the world is the Solar Energy Generating Systems facility in California, which has a total capacity of 354 megawatts...

  • Solar power plants in the Mojave Desert
    Solar power plants in the Mojave Desert
    There are several solar power plants in the Mojave Desert which supply power to the electricity grid. Solar Energy Generating Systems is the name given to nine solar power plants in the Mojave Desert which were built in the 1980s. These plants have a combined capacity of 354 megawatts making them...

  • Solar thermal energy
    Solar thermal energy
    Solar thermal energy is a technology for harnessing solar energy for thermal energy . Solar thermal collectors are classified by the United States Energy Information Administration as low-, medium-, or high-temperature collectors. Low-temperature collectors are flat plates generally used to heat...



External links